So, in order to fix the rollagas mk2...let's start with what the problem was on mine. It was leaking. And it turned out, to be a cracked weld on the gas tank, which is made of brass or bronze of sorts...most of it's one solid piece, but I'm guessing the way the gas tank is constructed, they first CNC out the tank, then put a cover over the hole they drilled and weld it in place to form the tank. I cracked this by dropping my lighter. Numerous times. It's taken a fall on concrete once, and survived, so I'm not sure what drop caused it, but it was leaking. I took a torch and re-worked the weld a bit. It was sloppy and make-shift, but it no longer leaks. I made like 2 failed attempts before I was successful, however.

Please read all of these instructions entirely before you start, do not read as you go, it will be a lot more painful.

First, take the pin out on the lid. Same way as on a dupont. Using a really thin screwdriver bit from one of those micro-screwdriver sets is your best bet. Do not try to use something without any leverage like a paperclip or something unless your pin is really loose it will be more likely to damage the case of your lighter than to get the pin out.

Okay, next step, well you can either take out the flint mechanism now or later, but it'll have to come out at some point so you might as well do that next. The screw is REVERSE THREAD! Righty-loosey? Yeah. Be careful. Open the flint holder like you're taking a flint out, take the screw out, and then pull the whole thing apart. There's a spring under it, be careful not to lose it or let the flint pusher launch it out like a rocket as it did with mine, ha. Once all that's off, you're ready to remove the bottom.

Unscrew the gas height adjuster until it comes out. There's a white plastic piece that goes inside it, be careful it doesn't fall out and put the whole piece aside. There should be a screw under where that was, you can now take that screw out. There's now...another screw. How surprising! Take that out as well. The whole thing is held together by friction, essentially. There's essentially 3 metal plates, 2 of which have little ridges that stick out and wedge into slots that are cut into the side of the case. The third plate, is the shiny piece out the outside, and that kind of just goes on top and makes the whole thing more sturdy I guess. There's going to be 2 little black rubbery/foamy things that are basically there to help you put the thing back together a bit easier, and the smallest of the 3 metal plates also has a long foamy/rubbery thing attached to it and again it assists with re-assembly. Be sure to observe how all this goes together, as putting it back together will be quite tricky otherwise!

Once that's out, you should be able to now slide the lighter out the bottom. Well, not the entire lighter, just the gas tank, and this allows you to finally remove the roller as well. Once that's out, you can reach the screw that holds the top of the lighter on, IF YOU SO DESIRE. Note that you may not actually need to remove this part, depending on what's broken with your lighter. In my case, the gas tank was all I really needed to take out, but I opted to take it apart completely so that I could clean it thoroughly while I was at it....Sooo...remember how the bottom was held on with that friction fit and the two grooves in the side? Well, the top is too, however it's a little simpler. It's just one metal piece that friction fits using the top metal piece of the case as leverage. This whole thing is a bit tricky to get out and back in, but it will go back together with some patience.

And well, the rest should be pretty explanatory if you've ever seen how a lighter works, the fuel release is a pretty typical style mechanism, but I haven't had to take mine apart fortunately. On the gas tank itself, I took out the fill valve while I welded it, I didn't want to cause any rubber seals to melt. This piece came out pretty easily, but spanner wrenches would probably be the most proper way, but mine wasn't so tight so I could remove it just with friction and some pliers on the shaft...

Thanks for the detailed walkthrough, some pics would be nice if you have them, since I imagine the new ones are put together a little differently to the diagram posted by simonthorby. I've gone over it a few times thinking I might open up my rollagas out of general curiosity but I may mess it up and void the warranty.

Btw, that first part you mention about removing the pin, would that be the one holding the hinge together for the body and cap or is there another pin within the cap assembly?